Project A06:
Source apportionment of UTLS refractory aerosol and ice-nucleating particles

Brief Summary

Aerosol in the UTLS region may originate from extraterrestrial and terrestrial sources or may be secondarily formed in the atmosphere by gas phase or heterogeneous reactions. Refractory particles act as surface for heterogeneous reactions, but in most cases originate from space or the Earth’s surface. The main goal of this project is to realize an almost artefact free sampling of UTLS aerosol particles and to characterize the received particle samples by off-line electron microscopic individual particle analysis (EMIPA). By Transmission Electron Microscopy (TEM), conventional Scanning Electron Microscopy (SEM) and Environmental Scanning Electron Microscopy (ESEM) in Darmstadt three complementary methods will be applied. By use of all these electron microscopic methods data about the elemental composition, mineralogical phase composition, mixing state (internal/external mixtures, coatings, agglomerates, heterogeneous inclusions), volatility and aging of the refractory particles and low-volatility compounds in UTLS will be received. On base of this explicit and wide data set source apportionment will be performed, which will help to understand the main pathways of particulate components towards UTLS. It will contribute to the questions on how surface emissions influence the UTLS aerosol, how significant the contribution of meteoric smoke is, to what extent the particles are modified, and what would be implications of the composition, e.g., for optical properties and in this way for the radiation budget. Beyond that we will run a second airborne sampling system, which is optimized for the off-line physicochemical characterization of the ice nucleating properties of the UTLS aerosol particles. The physicochemical characteristics and the ice nucleating capabilities will be analyzed by the new established coupled analyzing method of the Frankfurt Ice Nucleation Experiment (FRIDGE) and Environmental Scanning Electron Microscopy (ESEM). In the first step of this analyzing procedure in FRIDGE information about the ice nucleating properties of the UTLS particle samples under different temperatures and humidities are determined and will enable the assessment of potential ice-nucleating particle (INP) concentration in the UTLS. In the second step each identified potential INP can directly be analyzed in the ESEM, revealing size, chemical composition and mixing state of the INPs. These investigations will contribute to the question which potential ice nucleating particles are present in the UTLS region and if these INPs play an important role for the occurrence of clouds (cirrus formation) in the UTLS.

Members

Publications

Ebert, M., R. Weigel, S. Weinbruch, L. Schneider, K. Kandler, S. Lauterbach, F. Köllner, F. Plöger, G. Günther, B. Vogel, and S. Borrmann (2024): Characterization of refractory aerosol particles collected in the tropical upper troposphere-lower stratosphere (UTLS) within the Asian Tropopause Aerosol Layer (ATAL). Atmospheric Chemistry and Physics 24 (8), 4771-4788. doi: 10.5194/acp-24-4771-2024.